This invention relates generally to industrial baghouses and, more particularly, to a tensioning assembly for connecting bag filters to an overhead support.
Industrial and regulatory emphasis on environmental air quality may tend to increase efforts to develop techniques to improve effectiveness and efficiencies of methods and apparatus for separating and removing particulate matter from a fluid flow stream. At least one known technique for particulate removal is fabric filtration. Some known fabric filtration methods include the use of a baghouse and an associated bag filtration system employing bag filters. One fundamental scheme of operation of a bag filtration system is that a fluid that contains entrained particulate matter enters the interior section of a porous bag filter. The fluid transports through the bag filter fabric and exits the external surface of the bag filter. The particulates, depending on their size and chemical constituents, are captured on the interior surface of the bag filter and accumulate on that surface. This mode of operation is referred to as the filtration mode.
During extended operation of a bag filtration system in the filtration mode, particulates accumulate on an interior surface of the filter such that “caking” of the particulates occurs on the bag filter interior surface, thereby tending to reduce the efficiency of fluid flow through the bag filter fabric. Eventually a cleaning process is employed to remove the caked particulate. Some known processes of bag filter cleaning include manual methods that include removing the filtering system from service, often referred to as executing a system outage, and employing manual labor. Removing the system from service and employing manual labor tends to facilitate an increase in the expense of operating and maintaining the filtering system.
Some known alternate cleaning processes include remote bag filter cleaning and the employment of this process referred to as a cleaning mode of operation. Some of these known remote processes include a reverse flow-type bag filter cleaning sub-system. A reverse fluid flow process may include interrupting the flow of fluid from the interior of the bag filter to the external surface via the porous fabric and subsequently inducing a reverse fluid flow from the external bag filter surface to the interior surface through the filter fabric. The reverse fluid flow may contain sufficient force to dislodge the caked particulate matter from the bag filter interior wall. The process may be considered remote in that it may be initiated and controlled from a location external to the bag house and may eliminate some manual cleaning efforts. The process may also be automated.
Some known reverse flow cleaning processes may tend to induce sufficient force to collapse bag filters inward. This condition tends to reduce the effectiveness of the cleaning operation by at least partially collapsing bag filters such that dislodging the caked particulate matter is partially prevented. Increased tensioning of the bag filters improves resistance against the tendency to collapse. However, if the bag filters are stretched too tightly, the extended tension tends to induce a weakening of the fabric structure and the bag filters may wear more quickly. Also, cycling between filtering mode and cleaning mode induces varying tensions in the fabric and may cause the fabric to stretch. Varying tensions in the filter bags outside of pre-determined tolerances may increase the number of system outages, manual inspections and subsequent manual re-tensioning of the bag filters. If left unattended, the stretching of the fabric may eventually result in a failure of the bag filter. Alternately, if the tension of the bag filters is such that the bag filters are too loose, the bag filters tend to bend or flex such that they rub against one another or against other system components, resulting in bag filter abrasion and possible failure as well as negatively impact cleaning efforts as described above.
Some known baghouse filtering systems use a bag filter tensioning assembly that includes a spring to attempt to induce a substantially constant tension in the bag filters. However, some of these known spring tensioning assemblies employ springs that induce sufficient tension in the bag filters during filtration operations, yet may not compress readily and thereby may not increase tension sufficiently during cleaning operations to substantially resist the tendency of bag filter collapse. Also, some known spring tensioning assemblies induce sufficient tension to resist bag filter collapse during cleaning operations, yet may also induce excessive tension during filtration mode operations.